Thank you,
yep, there is an issue in the shrink part. I think growing is okay, it happens by collecting other pixels. But shrink is not visible, because if any pixel dies, it's game over. (This is not what I planned at the beginning, I wanted to remove one pixel when colliding with obstacles. Anyway, I thought this way was better than shrinking for my game.)
And I agree, the shrink part is missing, there is only grow part!